Electrical impedance tomography (EIT) is a known medical imaging technique in which an image of the conductivity or permittivity of part of a patient is inferred from electrical measurements sensed at the surface of the patient. Typically, conducting electrodes are attached to the skin of the patient in a pattern that encircles an area of interest. Small alternating currents on the order of a few nano-amperes (nA) to several mili-amperes (mA) are applied to some or all of the electrodes at a frequency that is generally in the kilo-Hertz (kHz) range. The resulting electrical potentials are measured, and the process repeated for numerous different configurations of applied current.